Personal computers utilize circuit carrying boards housed in the computer's chassis as platforms to secure and interconnect individual electronic components. In order to provide consumer flexibility, these circuit boards are frequently designed to accommodate additional circuit boards, or expansion cards, to provide additional and/or alternative functionality. For example, many personal computer circuit boards are designed with expansion card slots for standard bus interfaces, such as ISA (Industry Standard Architecture) and EISA (Extended Industry Standard Architecture), into which expansion cards for peripheral devices, such as hard disk controllers, tape controllers, modems and other I/O controllers, may be connected. Many of these expansion cards require connections to devices and equipment external to the computer chassis itself. Accordingly, access points in the computer chassis adjacent to the expansion card connectors are provided to allow for connection between the expansion cards and peripheral devices.
In order to provide insulation against electromagnetic radiation and noise, and to protect against dirt and dust invasion, it is desirable to seal the access points in the chassis to the extent not required for external connection by an expansion card. Accordingly, the typical expansion card is provided with a cover which seals the access point while providing for external connections. When there is no expansion card in place, as is often the case when the computer leaves the factory, a filler panel is provided to seal the associated access point.
In order to provide economies of production, and for ease of use, a standard filler panel mounting arrangement has been developed for typical Microsoft DOS/Windows based personal computer chassis designs. The standard filler panel is essentially an L-shaped metal shield which incorporates a mount having a retention slot in the top side through which a screw is driven to secure the filler panel through a threaded hole to a lip in the chassis, or expansion card cage mounted within the chassis, adjacent the access point. The standard expansion card incorporates a similar access point mount, minus the panel, having a retention slot through which a screw is driven to secure the card with the chassis adjacent to the access point.
Unfortunately, the foregoing access mount, whether part of a filler panel or expansion card, provides for a retention slot having a length such that the placement of the filler panel or expansion card may vary relative to the threaded hole while the screw is driven. In the filler panel embodiment this results in inconsistent filler panel placement that may leave openings in the chassis between the misaligned filler and access point. This problem exhibits less frequently in the expansion card embodiment because the position of the expansion card and its related mount is fixed by the location of the expansion card connector, and the screw attachment to the chassis is merely used to provide additional horizontal and vertical support to protect the expansion card against shock and the like.
Because the filler panels are easily moved during assembly, the assembler must utilize two hands to secure the filler panel in the chassis (one hand to hold the filler panel in place and the second hand to drive the screw), thereby increasing assembly time. Moreover, by requiring a screw in the assembly process, an additional part for each expansion slot must be inventoried and maintained. Furthermore, screws may be lost or lodge against the circuit board, causing shorts and potential catastrophic failure of the system. Thus the foregoing access point mount, particularly in the filler panel embodiment, adds to installation time and increases inventory problems.
One solution to remedy these failures is to design the filler panel to provide a lip extended down from the back of the top of the filler panel which rests in a slot formed in the chassis. After the filler panel is in place with the lip holding it in position, a bar is lowered onto the top of the filler panel to hold it in place and to prevent horizontal movement away from the card cage. However, a draw back of this solution is that it cannot be used with conventional chassis designs that do not provide for such a slot to hold the panels in place.
As a consequence, what is needed is an improved alignment and retention mechanism for the access point mount of a filler panel or expansion card installed in the chassis of a computer.